First build, plenty of questions

[tremblaylive]

Hi everyone!

I am aiming for a somewhat ambitious first build: a Hiwatt DR103. The layouts I have seen online (especially on hiwatt.org) are very easy to read and it leads me to believe that the "technical" part of the execution shouldn't be complicated.

I do however have some questions:

While reading the bill of materials (http://hiwatt.org/DIY/BoM.html) I came across very specific component specifications.
Ex: In the electrolytic capacitors -- 100 uF 100 volt. Would there be an adverse effect if I had components that had a significantly higher voltage rating than those listed? (Ex: 100uf 350volt)

Am I biting off way more than I can chew?

If any of you ended up completely scratch building a similar amp (DR504, DR103, DR103 Lead, etc) -- approximately what was the cost like?

I've read that carbon film resistors are a good "in between" with metal films being very sterile and carbon comp being more colored (and therefore more noisy) -- is this also your experience?

Thanks in advance, sorry for the wall of questions

[xtian]

Welcome to TAG!

I am aiming for a somewhat ambitious first build: a Hiwatt DR103. The layouts I have seen online (especially on hiwatt.org) are very easy to read and it leads me to believe that the "technical" part of the execution shouldn't be complicated.

True, Huss's layouts and schematics are great.

While reading the bill of materials (http://hiwatt.org/DIY/BoM.html) I came across very specific component specifications. Ex: In the electrolytic capacitors -- 100 uF 100 volt. Would there be an adverse effect if I had components that had a significantly higher voltage rating than those listed? (Ex: 100uf 350volt)

In general, no, using parts with higher voltage rating is not a problem. But 100uF/100v is probably a bias cap, and using a 350v monster in that spot may be a tight fit.

Am I biting off way more than I can chew?

I dont' know. What's your electronics experience? Soldered much? Can read a schematic? Planning to drill your own chassis?

If any of you ended up completely scratch building a similar amp (DR504, DR103, DR103 Lead, etc) -- approximately what was the cost like?

You can expect to pay $400-$800 for parts, not including a cabinet to put it in.

I've read that carbon film resistors are a good "in between" with metal films being very sterile and carbon comp being more colored (and therefore more noisy) -- is this also your experience?

No. Resistors serve a purpose. The "mojo" with carbon is that it's not accurate, it drifts over time and with heat, and SOMETIMES, this variance makes magic. I use carbon film sometimes because that's what I bought in the early days, but now I'm perfectly happy with metal film. The values are precise, they're cheap, and they work like they should.

[tremblaylive]

Thanks for the thorough response xtian!

I haven't soldered in years, but I will definitely be tinkering a lot in the near future to get the confidence back. I'm reading a lot of material on how to read schematics and i'm using paired schematics and layouts to "test my understanding".

At that cost, it actually makes it a hell of a lot more interesting to learn to build amps vs buying them!

As far as the chassis goes, I will be purchasing that as I think it is worth it (found some relatively cheap ones with good specs)

What suppliers do you use for purchasing your parts? There are an abundance of websites with a huge variance in price (ex: taydaelectronics is DIRT CHEAP for resistors).

[Phil_S]

Welcome to TAG! You may find that you are spending a great deal of time trying to obtain lowest cost on parts. This can be a fools errand.

One big factor is postage/shipping. You can't just buy a little bit because your 10¢ part actually costs $10.10 because of shipping. To split an order over two suppliers requires you to overcome the $10 in extra shipping and that can be very hard to do.

Your time is worth something. At some point, you'll realize you've spent too many hours trying to wrangle your order down to lowest cost. It isn't worth that much time.

Try to get it all in one place if you can. Look for fair pricing, not lowest cost and look for what you want where not too much compromise is required. When you have more experience, you may find there is an advantage to splitting your order. At this stage, it is likely to feel quite burdensome. There is everything right about paying a little more for convenience and service. That said, items to split from your order are likely to be the chassis,transformers, and cabinet.

Regarding your question about using a 350V cap where the spec is 100V rated cap, you will be able to see on-line the size of each. While there will be variance between brands, there is still a relative range that will demonstrate xitan's point. A 100u 100v axial lead Sprague TVA is .438" x 1.5". The same in 350V is 1" x 2.625". [source: August 2008 Mouser paper catalog} Cost will be another factor, with the high voltage ones costing considerably more.

I've seen arguments both ways on what constitutes biting off too much. Some folks will say, "Build a Champ or some AX84 amp first to get your feet wet. There's a learning curve." Others will say, "Build what you want. Take your time. Anything is possible if you put your mind to it." I used to side with the Champ/AX84 crowd. I've moved away from that thinking in favor of saying it really depends on the person whether you can take on a more complex project successfully.

Ask for guidance. You'll get some.

[MakerDP]

Welcome aboard.

I would suggest doing a well documented kit for your first go at this. There is a LOT of value in step by step instructions and technical support, especially with a more complicated build like a HiWatt.

Consider this kit: http://www.trinityamps.com/product/tri ... watt-kit/

It is a lower wattage (6V6) version of a DR103 for a great price. It comes with everything except a head cabinet.

My first build was a Trinity kit. The documentation is fantastic, he uses only premium parts and his service and support are great.

[xtian]

What suppliers do you use for purchasing your parts? There are an abundance of websites with a huge variance in price (ex: taydaelectronics is DIRT CHEAP for resistors).

I get 90% of my parts from tubesandmore.com and mouser.com.

[tremblaylive]

Thanks for the great answers guys!

I had seen the trinity kits, and they look terrific! The only thing that stopped me from pulling the trigger is the fact that it is lower wattage and has a different power section. I kind of want the huge headroom the bigger iron will get me, as I will be using the amp as a pedal platform.

I was hesitating between building a DR103 and DR504, but figured that I could always run the 103 with only 2 output tubes to get approximately the same output power as the 504, while having the option to double it up if I wanted to.

I could always contact triwatt and see if they would consider making a kit for the bigger sibling of their amp

[Phil_S]

2 tubes is still 90% of what 4 tubes will do in terms of perceived volume. To get to half volume from a 100W amp, it needs to get down to about 10W. I'm not real familiar with Hiwatt amps, but I'm going out on a limb and saying you'll still get plenty of headroom with the 2 tube model. 100W is a real monster. You'll save some money on transformers with a 50W amp and you might not miss that other 50W. I'm sure you won't miss the extra weight. Maybe someone who knows these specific amps can chime in?

[MakerDP]

The iron on the Trinity kit will also support KT66's I believe. That would probably sound incredible... a DR103 preamp into KT66's would be pretty sweet.

FWIW, I have NEVER wished I had more than two 6V6 tubes can deliver. I gig regularly with my 20-ish watt amp and do lots of "clean" blues with it and it has never been turned up past about 2:00 on the master volume. If we play somewhere where it's not enough, a mic goes in front and it goes through the PA with everything else on stage.

I also pretty much exclusively use tubesandmore.com and mouser as well. Occasionally I will buy ClassicTone iron but the free shipping and almost always one-stop-shopping with tubesandmore.com pretty much eliminates any savings and/or hassle with trying to find the best prices and worrying about sketchy quality in my mind. Transformers are expensive to ship and when you can get that for free with a $90+ order that saves some good $$$. Plus my order comes in just a couple days since I am only one state over.

[M Fowler]

I think that Triwatt is harder to build then a DR103 based on the layout.

Use 100uf/150v but the 100uf/100v and 100uf/150v are readily available since they are used in many bias circuits.

[JazzGuitarGimp]

I've worked in the electronics industry since 1979. I have tons of experience in building prototype circuits from scratch, drilling and punching chassis', etc. Yet when I decided to build my first tube amp (2006), I bought a kit; the Trinity Tweed Deluxe kit, to be exact. Since then I've built a handful of amps from scratch. So I definitely wouldn't discourage you from starting with a kit.

As for complexity / biting off more than you can chew, I agree with Phil-S. Here's a strange analogy / association: when I was 30, a good friend took me to the ski slopes and taught me how to ski. We spent the first day with him teaching me how to snow plow down the mountain. That evening, he told me that he would teach me how to parallel ski the next day, and added that once I learned how to do this, I would never go back to snow-plowing again. At the end of the second day, I couldn't help but ask "why in the heck did we waste a whole day learning how to snow plow?" There are many ways to skin a dog (sorry, I'm a cat lover) or, build an amp. Many people are quite successful with a paint by numbers approach - not really knowing anything about the circuits and how they function. At the other end of the spectrum, you've got guys who know the theory, run the calculations, and obsess over every last detail. And there's every level of builder in between. As long as you understand and respect the "risk of human life / dangerously high voltages" aspect of doing this, you will be okay. And like Phil_S said, ask for advice; this forum is comprised of a great group of kind, knowledgeable people who are quick to jump in and "help solve the problem".

Welcome aboard!

Lou